Hello! I would love some help.

Today my girlfriend's younger cousin got engaged which caused her to get angry and cry for hours. Even though she's the older one, she has felt behind in everything in life (from getting a license to dating to renting a house, etc.). She really wanted to be the first one to be engaged and married (even though her cousin and fiancé have been together for almost 8 years now). She thinks that because her cousin has her life "more together" that makes her a failure and her family won't care about her life. She keeps talking like she is in a competition with her cousin.

Also, she was scared about graduating from university this spring (before said cousin), but was feeling better when we invited her family and they were excited about going. Now she thinks nobody will care.

I have been trying to make her feel better but I really do not know what to say. If anyone has any advice that would be much appreciated!